Current Trends in Biosolids Management & …

1 Current Trends in Biosolids Management & treatment Jay Kemp, PE, BCEE Bill Marten, PE, BCEE Black & Veatch Donohue & Associates 35th Annual Spring Biosolids Symposium March 21, 2017 Stevens Point, WI Page 2 | March 21, 2017 35th Annual Spring Biosolids Symposium Presentation Topics High Level Overview Discussion of: Digestion Aerobic Anaerobic Nutrients Issues, Challenges, Recovery Takeaways Page 3 | March 21, 2017 35th Annual Spring Biosolids Symposium Aerobic Digestion Has Been Around a Long Time, What Could be New or Trending? Operational Mode Cycling Cycling Air On (Aerobic) and Off (Anoxic) Use of Membranes to Enhance Thickening Aerobic Digestion Page 4 | March 21, 2017 35th Annual Spring Biosolids Symposium Operational Mode Cycling Aeration ON Digestion occurring Oxygen is utilized for electron acceptor Ammonia is nitrified to nitrate Alkalinity is consumed & pH decreases Aeration OFF Digestion occurring Nitrate is utilized as electron acceptor (Energy Savings)

2 Nitrate is denitrified to nitrogen gas Alkalinity is recovered & pH increases Can Accomplish in Dedicated Reactor Zones or Single Reactor (Digester) Page 5 | March 21, 2017 35th Annual Spring Biosolids Symposium Process Control Aerobic: or Time Anoxic/Anaerobic: ORP or Time >Experiences Have Shown 50/50 Time Split Works Well Can Minimize Digested Sludge Production Long Cycle Times and Multiple Cycles in Each Operational Mode >Similar to Interchange Reactor Effect of the Cannibal Process Enhanced Digestion Due to More Effective Predation >Anaerobic Predation on Aerobic Organisms >Aerobic Predation on Anaerobic Organisms Aerobic Digestion Cycling Page 6 | March 21, 2017 35th Annual Spring Biosolids Symposium Eliminate Decanting, Use Membrane Filters for Solids Separation (Decanting)

3 Benefits Cleaner Decant Ability to Operate Digester at Much Higher TS Concentrations >From Typical 3% TS to TS >Increases treatment & Biosolids Storage Capacity, Possibly Delaying Need for Plant Expansions Aerobic Digestion: Membrane Thickening Page 7 | March 21, 2017 35th Annual Spring Biosolids Symposium Example: Kubota PAD-K Aerobic Digestion Aerobic Digestion: Membrane Thickening Page 8 | March 21, 2017 35th Annual Spring Biosolids Symposium Maximizing Biogas Production & Energy Use/Value High Strength Waste Receiving Effective Mixing Recuperative Thickening Staged Digestion Pre-Digestion Sludge treatment Anaerobic Digestion Trends Page 9 | March 21, 2017 35th Annual Spring Biosolids Symposium Electrical Pulses Mechanical Grinding High Heat With Pressure With Chemical treatment Pre-Digestion Raw Sludge treatment Page 10 | March 21.

4 2017 35th Annual Spring Biosolids Symposium Electrical Pulses Mechanical Grinding High Heat With Pressure With Chemical treatment Pre-Digestion Raw Sludge treatment Page 11 | March 21, 2017 35th Annual Spring Biosolids Symposium Heat & Pressure Approach Cambi Thermal Hydrolysis Pre-Dewatering All Sludge or Just WAS BioThelys Pre-Dewatering All Sludge or Just WAS Exelys Pre-Thickening Usually Just WAS In General: Utilize Steam Raise Sludge Temperature to 330-350 Deg F Raise Pressure to 90-130 psi Rapid Depressurization All Capable of Class A Page 12 | March 21, 2017 35th Annual Spring Biosolids Symposium Example Heat & Pressure: Exelys Page 13 | March 21, 2017 35th Annual Spring Biosolids Symposium Heat & Chemical Approach Pondus TCHP Pre-Thickening All Sludge or Just WAS In General.

5 Utilize Hot Water Raise Sludge Temperature to ~150 Deg F Use Caustic to Raise pH to ~11 Hydrolization Lowers pH Capable of Class A Page 14 | March 21, 2017 35th Annual Spring Biosolids Symposium Example Heat & Chemical: Pondus TCHP Page 15 | March 21, 2017 35th Annual Spring Biosolids Symposium Process Complication vs Operating Costs Dewatering vs Heating Water Total Present Worth Considerations Capital Cost Operating Cost Negatives >Heat, Chemical, Processing Energy Operating Cost Positives >Increased VSR of 10-20% Possible >Potential Class A Performance characteristics will be highly site specific pilot testing recommended.

6 Pre-Digestion treatment Considerations Page 16 | March 21, 2017 35th Annual Spring Biosolids Symposium Nutrient Issues/Challenges Page 17 | March 21, 2017 35th Annual Spring Biosolids Symposium Nutrient Issues/Challenges: Phosphorus Page 18 | March 21, 2017 35th Annual Spring Biosolids Symposium NR 217: 20+ Years of Effluent P Limits Biosolids Impacts Higher P Content Increased Sludge Quantities Nutrient Issues/Challenges: Phosphorus Tertiary treatment Effluent Secondary treatment (Bio-P) Raw WW Primary treatment Chemical Feed Chemical Feed P P Page 19 | March 21, 2017 35th Annual Spring Biosolids Symposium Very Low Water Quality Based Effluent Limits Will Result in: Higher Levels of Removal Required Alternative Compliance Approaches such as Trading, Adaptive Management , Variances Revisions to NR 217 A New Pinch on P More P More P More P.

7 And Potentially More Restrictions on Biosolids Reuse Tertiary treatment Effluent Secondary treatment ( Bio-P) Raw WW Primary treatment Chemical Feed Chemical Feed Chemical Feed Page 20 | March 21, 2017 35th Annual Spring Biosolids Symposium ..Due to the Required Anaerobic/Aerobic Cycling Bio-P Presents Some Unique Biosolids TimeAnaerobicAerobicConcentrationSoluble BODS oluble OrthophosphorusPage 21 | March 21, 2017 35th Annual Spring Biosolids Symposium Anaerobic Zone => VFA Uptake & SP Release Bio-P Carbon Storage Polyphosphate VFA s Soluble PO4-P (Energy) Page 22 | March 21, 2017 35th Annual Spring Biosolids Symposium Aerobic Zone => Biometabolism of Carbon (Growth & Oxidation) & Soluble P Uptake Bio-P O2 CO2 and H2O and More Cells (Cell Synthesis)

8 Soluble PO4 Energy Carbon Storage Polyphosphate Page 23 | March 21, 2017 35th Annual Spring Biosolids Symposium Soluble PO4-P Release Thickening/Dewatering Increased SPO4-P in Filtrate/Centrate Sidestreams Increased SPO4-P Also Occurs With Aerobic Digestion, Just Not to Same Extent Most Bio-P Related Biosolids Challenges Are Associated With Anaerobic Digestion Carbon Storage Polyphosphate VFA s SPO4-P (Energy) Anaerobic Conditions with Lots of VFAs Page 24 | March 21, 2017 35th Annual Spring Biosolids Symposium One (Now Familiar) Bio-P/Anaerobic Digestion Sidestream ! Page 25 | March 21, 2017 35th Annual Spring Biosolids Symposium Sidestream Control Strategies Can Also Control Struvite Or Simple Dilution of Filtrate Can Work Too Luckily, We Understand Struvite & Controlling It Anaerobic DigesterGravity Belt ThickenerThickened SludgeGBTF iltratePolymerFerric Chloride AdditionPage 26 | March 21, 2017 35th Annual Spring Biosolids Symposium Such Sidestream/Struvite Control a Standard Component of Our Designs Eau Claire DSD Thickening Filtrate Line Page 27 | March 21, 2017 35th Annual Spring Biosolids Symposium The New Bio-P Ugly.

9 Impaired Dewatering of Anaerobically Digested Sludge 8 Tall Push Walls 3-4 Foot Typical of Unusable Wall Height Page 28 | March 21, 2017 35th Annual Spring Biosolids Symposium Dewatered Cake Looks Normal & Dry Reduction in Cake Dryness of 5-8% TS Stacking Height Often Half of Expected Being Experienced at Many Plants Beloit, WI Sun Prairie, WI Marquette, MI Hampton Roads Sanitary District Atlantic & Nansemond Plants, VA Met Council Environmental Services Empire & Blue Lake Plants, MN Metro Denver, CO Impaired Dewatering of Anaerobically Digested Bio-P Sludge Observations Page 29 | March 21, 2017 35th Annual Spring Biosolids Symposium Differences in Extra-Cellular Polymeric Substances (EPS)

10 /Soluble P Concentration of Digested Sludge Evidence that soluble Ortho-P binds water to solids >Possibly due to increased presence of EPS/EPS binds water >Lower digested sludge soluble Ortho-P => higher cake TS Divalent Cation Bridging Suspected Causative Factors Page 30 | March 21, 2017 35th Annual Spring Biosolids Symposium Divalent Cation Bridging Theory Courtesy of Sprouse, 2013 Page 31 | March 21, 2017 35th Annual Spring Biosolids Symposium Prominent Divalent Cations Are Mg2+, Ca2+ and Fe2+ Prominent Monovalent Cations are Na+ and K+ Divalent Cation Bridging Theory To Help Understand This, Let s Take a Step Back Page 32 | March 21, 2017 35th Annual Spring Biosolids Symposium Anaerobic Digestion of Bio-P: Potential Effect on Cation Ratios Carbon Storage Polyphosphate VFA s PO4- (Energy) Mg2+ K+ NH4+ Struvite And What About That Potassium?